Following downsizing of electronic apparatuses, a demand for a semiconductor device to which a QFN (Quad Flat Non-leaded Package) is applied increases.
The semiconductor device to which the QFN is applied is prepared by a MAP (Molded Array Packaging) system, for example. According to the MAP system, a plurality of semiconductor chips are collectively sealed with sealing resin on a lead frame, and thereafter cut into individual semiconductor devices each including one semiconductor chip.
The lead frame is made of copper, for example. The lead frame includes a lattice-type supporting portion. A rectangular die pad and a plurality of leads are formed in each rectangular region surrounded by the supporting portion. The lead is arranged on the periphery of a die pad. Each lead is formed in a long shape having a base end portion connected to the supporting portion and a free end portion extending toward the die pad.
After the semiconductor chip is die-bonded onto each die pad, a terminal formed on each semiconductor chip and the upper surface of the lead on the periphery thereof are connected (wire-bonded) to each other through a bonding wire. When wire bonding of all semiconductor chips is completed, the lead frame is set in a molding die, and all semiconductor chips on the lead frame are collectively sealed with resin. Thereafter a dicing saw is introduced from the side of the lower surface of the lead frame along dicing lines set on the supporting portion, so that the supporting portion and the sealing resin on the supporting portion are removed. Thus, each lead is separated from the supporting portion, and each individual semiconductor device is obtained.
In the semiconductor device, the lower surface of each lead is exposed on the lower surface of the sealing resin, and mounting of the semiconductor device on a mounting substrate is accomplished by bonding the lower surface of each lead to a land on the mounting substrate (a wiring board). In the semiconductor device to which the QFN is applied, there is no extension of the lead from the side surface of the sealing resin, whereby the mounting area can be remarkably reduced as compared with a semiconductor device to which a QFP (Quad Flat Package) is applied.    Patent Document Japanese Unexamined Patent Publication No. 2001-257304